Fuel temperature compensator for fuel injection pumps

ABSTRACT

A device for single plunger distributor type fuel injection pumps having metering sleeve fuel control for automatically compensating for changes in fuel temperature. The fuel control surface of the metering sleeve is provided with a plurality of saw-tooth shaped grooves which cooperate with the plunger spill ports to control injection duration depending upon the rotational disposition of the sleeve. Sleeve rotation is produced by the expansion or contraction with fuel temperature change of a temperature compensating element bearing against the sleeve. With injection cutoff being determined by the relation of the spill ports with inclined surfaces of the sleeve grooves, the rotation of the sleeve upon increased fuel temperature in a direction opposite to the direction of plunger rotation will delay the opening of the spill ports and hence effect a longer injection interval to compensate for the reduced viscosity and heat content of the fuel.

United States Patent Galis et al.

[ 51 3,689,200 1451 Sept. 5, 1972 [54] FUEL TEMPERATURE COMPENSATOR FOR FUEL INJECTION PUMPS [72] inventors: Leon A; Galis, Ludlow; Donald E.

" Valentin, Westfield, both of Mass.

[73] Assignee: AMBAC Industries, Inc., Springfield, Mass.

[22] Filed: April 19, 1971 [21] Appl. No.: 135,035

Dreisin ..417/485 X Primary Examiner carlton R. Croyle Assistant Examiner-Richard E. Gluck Attorney-Howson & l-lowson 571 ABSTRACT A device for single plunger distributor type fuel injection pumps having metering sleeve fuel control for antomatically compensating for changes in fuel temperature. The fuel control surface of the metering sleeve is provided with a plurality of saw-tooth shaped grooves which cooperate with the plunger spill ports to control injection duration depending upon the rotational disposition of the sleeve. Sleeve rotation is produced by the expansion or contraction with fuel temperature change of a temperature compensating element bear: ing against the sleeve. With injection cutoff being determined by the relation of the spill ports with inclined surfaces of the sleeve grooves, the rotation of the sleeve upon increased fuel temperature in a direction opposite to the direction of plunger rotation will delay the opening of the spill ports and hence effect a longer injection interval to compensate for the reduced viscosity and heat content of the fuel.

8 Claims, 7 Drawing Figures PATENTEDSEP 51912 SHEEI 1 UP 2 INVENTORS LEON A. GALIS DONALD E, VALENTINE f 2wWLJ/2I w/zW/Z- ATTYS 1 FUEL TEMPERATURE COMPENSATOR FOR FUEL INJECTION PUMPS The present invention relates generally to fuel injection pumps and more particularly to a fuel temperature compensator for single plunger distributor type pumps having metering sleeve fuel control.

In the absence of a compensating mechanism, the effective fuel delivery of a fuel injection pump at a constant throttle setting decreases with increase in fuel temperature to such a degree as to result in a significant reduction of power at elevated temperatures. In equipment such as diesel farm tractors, the fuel tanks are generally mounted over the engine, causing the fuel to be delivered to the engine at temperatures substantially higher than ambient. A power reduction then occurs since the heated fuel is less dense, and considered on a volumetric basis as metered by the pump, has a lower heat content. In addition, the heated fuel being less viscous, leakage past the pump metering elements and the nozzle valves is increased with a consequent decrease in fuel delivery to the engine. Thus the reduced volumetric delivery of the pump and the lower heat content of the fuel at elevated fuel temperatures combine to reduce power output.

In the present invention, a fuel temperature compensator provides a variation in the duration of fuel injection in accordance with variations in fuel temperature to effect a larger volumetric injection at higher temperatures to compensate for the reduced heat content of the fuel and increased leakage tendency due to its decreased viscosity. In a single plunger distributor type pump, fuel metering is typically effected by a fuel control sleeve slidably disposed on the plunger in a fuel sump and selectively variable in axial position to control the opening of a plunger spill port into the sump and hence the duration of the injection interval.

The present compensator mechanism comprises a plurality of grooves in the control surface of the sleeve adapted to cooperate with the spill port or ports to vary the injection cutoff in accordance with the rotational position of the sleeve on the plunger. The sleeve rotation is controlled by a temperature sensitive fuelcompensator element extending into the sump, the expansion and contraction of which provide a corresponding rotation of the sleeve and hence a variation of the injection interval as a result of the variation in the position of the sleeve grooves with respect to the path of the plunger spill port or ports. The axial movement of the sleeve on the plunger is not restricted by the compensator mechanism, and the governor or manual fuel delivery controls function in a conventional manner in conjunction with the compensator throughout the speed range of the engine.

It is accordingly a first object of the present invention to provide a device for fuel injection pumps for automatically compensating for changes in fuel temperature and the accompanying changes in fuel heat content and pump leakage characteristics.

An additional object of the invention is to provide a device of the type described which is particularly adapted for fuel temperature compensation in single plunger distributor type fuel injection pumps having metering sleeve fuel control.

A further object of the invention is to provide a fuel temperature compensator as described of a simple, inexpensively fabricated design which can readily be incorporated into existing pump designs.

Additional objects and advantages of the invention will be more readily apparent from the following detailed description of an embodiment thereof when taken together with the accompanying drawings in which:

FIG. 1 is a partial vertical sectional view through a fuel injection pump showing the details of the hydraulic head thereof including a fuel temperature compensator in accordance with the present invention;

FIG. 2 is a sectional view taken along line 2-2 of FIG.-1;

FIG. 3 is an enlarged view taken along line 3-3 of FIG. 2 and showing the position of the fuel control sleeve at a relatively low fuel temperature;

FIG. 4 is a view similar to FIG. 3 showing the position of the fuel control sleeve at the same throttle setting as in FIG. 3 but with the fuel at an elevated temperature;

FIG. 5 is a view taken along line 5-5 of FIG. 3 showing-in broken lines the manner in which the sleeve is rotated under the, influence of the temperature compensator element at elevated fuel temperatures;

FIG. 6 is a perspective viewof the fuel control sleeve; and

FIG. 7 is a graph showing the variations in fuel delivery with temperature change at a constant pump jection pump 12 is illustrated in section. With the exception of the fuel compensator mechanism to be described, the pump is essentially conventional and is of the single plunger distributor type shown in U. S. Pat. Nos. 2,518,473 and 2,965,087. The fuel metering in this type of pump is provided by a fuel control sleeve axially slidable on the plunger to control the opening of the plunger spill ports into the fuel sump.

Considering the specific details of the pump, the hydraulic head 10 is mounted within the bore 14 of the main pump housing 16, being sealed therewithin by means of seal rings 18 and 20. The hydraulic head includes a central vertical bore 22 within which a plunger i the hydraulic head, is directed under low pressure into the fuel pumping chamber 32 through the passage 36 when the plunger is disposed so as to open the passage.

The plunger 24 is simultaneously driven in reciprocation and rotation by a conventional drive means (not shown) and serves to pump fuel from the fuel pumping chamber 32 through the delivery valve 26 into fuel delivery passages 38 and 40. The fuel passes from passage 40 into a plunger annulus 42 which is aligned therewith during the injection interval. An'axial distributor slot 44 in the plunger communicating with the annulus 42 sequentially distributes the fuel to the fuel outlet passages 46 leading to the outlet ports 48 which are connected directly to the engine fuel injection nozzles. The outlet passages 46 and ports 48 are symmetritional disposition of the sleeve as well as its axial cally spaced about the bore 22 and are equal in number to the number of cylinders of the engine serviced by the pump. In the pump illustrated there are six outlet passages and ports.

Since the plunger stroke is constant, fuel metering is effected by relieving the fuel pressure in the fuel pumping chamber 32 during the pumping stroke, thus allowing the delivery valve 26 to close and cut off injection. The pressure in the fuel pumping chamber is relieved -by means of an axial bore 50 which extends from the upper end of the plunger to the radial passage 52 passing diametrically through the plunger and which defines spill ports 54 at opposite sides thereof. The plunger in the region in which the spill ports 54 are located passes through a fuel sump 56 in the hydraulic head which communicates as shown in FIG. 2 with the fuel supply annulus 34. The opening of the spill ports 54 into the sump 56 is selectively controlled by means of a fuel control sleeve 58 which is axially slidable on the plunger and is selectively positioned within the sump 56 by means of the pin 60 coacting with the groove 62 of the sleeve. The pin 60 is eccentrically mounted on a fuel control shaft 64 which is directly connected with the engine fuel control rod (not shown). For any given rotational position of the shaft 64, there will be a corresponding axial position of the sleeve within the sump, which sleeve position will determine the amount of fuel delivery by determining the point of opening of the spill ports into the sump during the pumping stroke of the plunger.

With the fuel temperature compensator element seated in position, the inner end 84 of the element ex- The pump structure and operation thus far described Y is conventional and typical of sleeve metering type single plunger distributor fuel injection pumps. The temperature compensator improvement of the present invention described below requires only a modification of the metering sleeve and the provision of a temperature compensator element cooperatively disposed with respect to the sleeve.

In the conventional pump of this type, the upper surface of the sleeve is a planar surface and the fuel injection terminates when the spill ports 54 rise above the sleeve upper surface. In the present invention, however, radial grooves 66 which in the embodiment illustrated have a waveform or saw-toothed sectional configuration are provided in the upper surface 68 of the sleeve and are located and are of such a shape as to make the injection cutoff point a function of the rotaposition on the plunger.

In the embodiment illustrated, the plunger as viewed from above as for example in FIGS. 2 and 5, is rotated in a counterclockwise direction and will thus due to friction tend to rotate the sleeve in the same direction. Preventing such rotation and serving to rotationally position the sleeve in accordance with fuel temperature is the temperature compensator assembly 70 mounted in the hydraulic head and extending into the sump 56 for engagement with the sleeve 58. The compensator assembly 70 comprises a cylindrical temperature compensator element 72 which is slidably fitted within a bore 74 of the hydraulic head. A set screw 76 in a larger threaded outer bore 78 is seated against the outer flanged end 80 of the temperature compensator element, the flanged end 80 seating against the shoulder 82 of the hydraulic head.

tends partially into the fuel sump 56. Within an axial bore 86 in the inner end of the element is mounted a flanged hardened metal wear tip 88. A shank portion 90 of the wear tip 88 extends into the bore 86, while a tapered nose portion 92 is adapted to engage a planar side face 94 of the sleeve. As shown in FIGS. 2 and 5, the compensator assembly is mounted in the hydraulic head so that the alignment of the assembly and particularly the nose 92 thereof is offset from the plunger axis in a direction providing a moment arm producing a clockwise rotation of the sleeve upon expansion of the element 72 when viewed from above as in FIG. 5.

The temperature compensating element 72, which in a preferred form of the embodiment is made from a synthetic material such as nylon, is adapted to'e xpand longitudinally with increase in fuel temperature, thereby urging the nose 92 of the wear tip against the face 94 of the sleeve to rotate the sleeve in the clockwise manner shown in broken lines iriFIGLfS. The temperature of the hydraulic head in the region of the temperature compensating element will approximate that of the fuel passing through the annulus 34 and sump 56, and the element 72 will accordingly by con-' duction and by virtue of the inner end portion 84 extending into the sump 56 be maintained at a temperature substantially equal to that of the fuel.

The manner in which the present invention operates is most readily understood by reference to FIGS. 3 and 4. In these two figures, the throttle position is the same and hence the axial position of the sleeve in the sump 56 is the same in each view. In FIG. 3, however, the fuel temperature is relatively low while in FIG. 4 the fuel is at a relatively high temperature. As a result, the temperature compensator element has expanded longitudinally in the view of FIG. 4 and the sleeve has thus rotated in a clockwise direction to the position 96 shown in broken lines in FIG. 5. As a result of this rotation of the sleeve, it will be noted that the plunger must travel upwardly a greater distance in FIG. 4 than in FIG. 3 before the spill ports 54 open, each view being taken just as the spill ports open into the grooves 66. This is caused by the wave-form or saw-tooth shape of the grooves and specifically the inclined edge 66a of each groove which is actually the control edge producing the desired fuel compensating effect. It is necessary that the slope of the edge 66a, which slope is in the direction of movement of the spill holes during the pumping stroke of the plunger, be of a flatter slope than the path of movement of the spill holes. Upon increased clockwise rotation of the sleeve, the spill holes will accordingly open into the grooves 66 at difierent points along the control edges 66a. The higher up the ports open on the control edge, the longer the injection interval and the more fuel is injected into the engine. This compensating effect is most visually evident by a comparison of the distance of the comparable points of spill hole opening from the upper surface 68 of the sleeve. In FIG. 3 a substantial distance D is noted, while in FIG. 4 a significantly smaller distance D results. The difference between the distance D and D' represents the additional length of the pumping stroke of the plunger during which fuel is injected into the engine to compensate for the fuel temperature increase.

In FIG. 7, fuel delivery is plotted over a typical fuel temperature range for a pump operating at 2,400 rpm, the graph showing fuel delivery with and without the present temperature compensator. Although the broken line curve representing the fuel delivery with temperature compensator actually increases with temperature, the graph does not take into account the lower heat content of the higher temperature fuel which when considered results in a relatively uniform power delivery of the pump over the entire fuel temperature range normally encountered in pump operation. The downwardly sloping curve of FIG. 7 representing fuel delivery without temperature compensation shows only the reduced fuel volume resulting from lower fuel viscosity. The power output is further decreased by the lower heat value of the fuel.

it will be apparent that other configurations of the grooves 66 may be employed and that the control edge 66a may have a curved configuration to produce a course extend to the peripheral edge of the sleeve although this is a convenient method of manufacture.

In the present embodiment, the plunger is provided with a pair of diametrically opposed spill ports and the grooves 66 are similarly diametrically arranged so that the same 'fuel temperature compensating effect is simultaneously provided at each spill port. A modification might have a single spill port communicating with the plunger bore 50, or, for example in the case of a four cylinder engine, as many as four spill ports spaced at 90 could be employed. The number of grooves 66 required in the sleeve depends on the number of cylinders in the engine, the number of spill ports in the sleeve, and the speed of the pump with respect to engine speed.

The rate at which the volumetric fuel delivery changes with fuel temperature can be readily determined with laboratory equipment and the heat content loss can be calculated. The proper degree of compensation can then be supplied by appropriate selection of the material (coefficient of thermal expansion) utilized as the compensating element, the length of the element, its offset location from the plunger, and the ramp angle of the control edge 66a of the grooves. The compensating effect may be changed by varying one or a combination of these factors.

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1 In afuel injection pump including a hydraulic head having a bore therein a plunger rotatably and slidably disposed within the bore, the bore end above the plunger comprising a fuel pumping chamber, means for providing a reciprocating and rotating motion of the plunger, means for delivering fuel to the fuel pumping chamber during a portion of the plunger cycle, delivery and distribution means for successively delivering fuel from the fuel pumping chamber to a plurality of pump outlet ports during compression strokes of the plunger, a passage in the plunger opening into the fuel pumping chamber and connecting the chamber with a spill port opening into a fuel sump in the hydraulic head, a fuel control sleeve slidably mounted on the plunger in the sung, and {Ema-ITS for selectively adjusting the axial posi on o e s eeve, e improvement comprising a plurality of fuel control grooves in said sleeve adapted to cooperate with said spill port to control the opening of said spill port into said sump during each plunger compression stroke, each of said grooves terminating at its inner end adjacent said plunger in a control edge, said spill port passing across one of said groove control edges during each pumping stroke of the plunger, a temperature-sensitive compensator assembly in said hydraulic head bearing against said sleeve and adapted to vary the rotational disposition of said sleeve in accordance with variations in the temperature of fuel in the hydraulic head, said groove control edges being so,

related to the path of travel of said spill port as to vary the axial plunger position at spill port opening with variation in the rotational disposition of the sleeve whereby a change in fuel temperature effects a rotational repositioning of the sleeve to produce a compensating change in the pump fuel delivery, a rise in fuel temperature resulting in increased fuel delivery.

2. The invention as claimed in claim 1 wherein said compensator element bears against said sleeve in a manner preventing rotation of said sleeve by the influence of plunger rotation.

3. The invention as claimed in claim 1 wherein said fuel control grooves have a saw-tooth sectional configuration.

4. The invention as claimed in claim 3 wherein the control edge of each said groove forms an acute angle with the sleeve surface in which the grooves are disposed, the path of travel of said spill ports intersecting said control edges throughout the range of rotation of said control sleeve.

5. The invention as claimed in claim 1 wherein said temperature-sensitive compensator means comprises a compensator element adapted to vary dimensionally with variations in fuel temperature.

6. The invention as claimed in claim 5 including a hardened metal wear plate extending from said element, said wear plate being adapted to bear against a planar face of said sleeve.

7. The invention as claimed in claim 1 wherein said compensator assembly is operative to produce linear motion in response to fuel temperature changes, said motion being directed along a line spaced from the plunger axis and lying in a plane perpendicular to the plunger axis.

8. The invention as claimed in claim 1 wherein said plunger includes a pair of spill ports connected with the plunger passage, said spill ports being in diametrically opposed relation. 

1. In a fuel injection pump including a hydraulic head having a bore therein a plunger rotatably and slidably disposed within the bore, the bore end above the plunger comprising a fuel pumping chamber, means for providing a reciprocating and rotating motion of the plunger, means for delivering fuel to the fuel pumping chamber during a portion of the plunger cycle, delivery and distribution means for successively delivering fuel from the fuel pumping chamber to a plurality of pump outlet ports during compression strokes of the plunger, a passage in the plunger opening into the fuel pumping chamber and connecting the chamber with a spill port opening into a fuel sump in the hydraulic head, a fuel control sleeve slidably mounted on the plunger in the sump, and means for selectively adjusting the axial position of the sleeve, the improvement comprising a plurality of fuel control grooves in said sleeve adapted to cooperate with said spill port to control the opening of said spill port into said sump during each plunger compression stroke, each of said grooves terminating at its inner end adjacent said plunger in a control edge, said spill port passing across one of said groove control edges during each pumping stroke of the plunger, a temperaturesensitive compensator assembly in said hydraulic head bearing against said sleeve and adapted to vary the rotational disposition of said sleeve in accordance with variations in the temperature of fuel in the hydraulic head, said groove control edges being so related to the path of travel of said spill port as to vary the axial plunger position at spill port opening with variation in the rotational disposition of the sleeve whereby a change in fuel temperature effects a rotational repositioning of the sleeve to produce a compensating change in the pump fuel delivery, a rise in fuel temperature resulting in increased fuel delivery.
 2. The invention as claimed in claim 1 wherein said compensator element bears against said sleeve in a manner preventing rotation of said sleeve by the influence of plunger rotation.
 3. The invention as claimed in claim 1 wherein said fuel control grooves have a saw-tooth sectional configuration.
 4. The invention as claimed in claim 3 wherein the control edge of each said groove forms an acute angle with the sleeve surface in which thE grooves are disposed, the path of travel of said spill ports intersecting said control edges throughout the range of rotation of said control sleeve.
 5. The invention as claimed in claim 1 wherein said temperature-sensitive compensator means comprises a compensator element adapted to vary dimensionally with variations in fuel temperature.
 6. The invention as claimed in claim 5 including a hardened metal wear plate extending from said element, said wear plate being adapted to bear against a planar face of said sleeve.
 7. The invention as claimed in claim 1 wherein said compensator assembly is operative to produce linear motion in response to fuel temperature changes, said motion being directed along a line spaced from the plunger axis and lying in a plane perpendicular to the plunger axis.
 8. The invention as claimed in claim 1 wherein said plunger includes a pair of spill ports connected with the plunger passage, said spill ports being in diametrically opposed relation. 